Forum Discussion
Srinivasan_G_31
Nimbostratus
NimbostratusEmail notification setup - DNS resolution
Hi,
I am setting up email notification for alerting on the LTM local traffic logs. Part of that i am verifying DNS resolution (ref SOL3664) by playing the "dig mx" command. But the LTM says it has failed to communicate with the mail server. Would like to know the following.
* What will be source IP from which this request goes? Is it some self IP of the LTM?
* What will be the source and destinaton TCP ports on which this communication happens?
Any help is appreciated.
Srini
3 Replies
Ajmal_2608Source IP depends on Where is the DNS server you are trying to reach?
If its on internet then try the selp IP which has access to internet possibly your LTM's external interface IP
DNS resolution works on UDP port 53 so this will be your destination port
No source port is required as it may be random, still if you want to have source port put a range from 0 to 65535 as source port range
Hope that helps
What_Lies_Bene1Cirrostratus
What version are you running please?
Just FYI, you can use a local hosts file entry if you want to avoid the DNS lookup.
- What_Lies_Bene1The source IP for the email or DNS packets will be the floating Self IP for whatever VLAN is used when the traffic leaves the device (so will depend on routing).
